Test material analysis using offset scanning meandering windings

• US 6,198,279 B1
• Filed: 07/09/1999
• Issued: 03/06/2001
• Est. Priority Date: 08/25/1995
• Status: Expired due to Term

• Current Assignee: Jentek Sensors, Inc.
• Original Assignee: Jentek Sensors, Inc.
• Inventors: Goldfine, Neil J.
• Primary Examiner(s): STRECKER, GERARD R
• Application Number:
  US09/350,502
• Time in Patent Office: 606 Days
• Field of Search: 324/227, 324/232-234, 324/236-243, 324/207.16, 324/207.17
• US Class Current: 324/232
• CPC Class Codes: G01B 7/16 for measuring the deformation in a solid, e.g. by resistance strain gauge
• CPC Class Codes: G01B 7/34 for measuring roughness or irregularity of surfaces
• CPC Class Codes: G01N 27/82 for investigating the presence of flaws

Abstract

A meandering winding magnetometer (MWM) includes a meandering primary winding and at least one sensing winding or coil on a membrane to be pressed against a test surface. The membrane may be supported on a flexible carrier which is translatable into a probe. Abutments in the probe press the carrier against the test surface but allow the carrier and membrane to conform to the test surface. One MWM circuit includes meandering primary and secondary windings. The return leads from the secondary winding return to connector pads in close alignment with the test array, while leads from the primary winding are spaced at least one wavelength from the array. In another MWM circuit, individual sensing loops are positioned within the meandering primary winding. The MWM circuit may be provided on an adhesive tape which may be cut to length.

Claims

1. A test circuit for analyzing a test material comprising:

a first meandering primary winding for imposing a first spatially periodic magnetic field in the test material, the magnetic field being periodic in a first direction;

a second meandering primary winding for imposing a second spatially periodic magnetic field in the test material, the second spatially periodic magnetic field being of the same periodicity as the first spatially periodic magnetic field, being periodic in the first direction and being offset from the first spatially periodic magnetic field by a fraction of a wavelength of the spatially periodic magnetic fields in the first direction; and

sensors adapted to sense a response of the magnetic field to the test material as the first and second meandering primary windings are scanned across the test material in a direction transverse to the first direction.

2. A test circuit as claimed in claim 1 wherein the fraction of a wavelength is one quarter wavelength.

3. A test circuit as claimed in claim 1 wherein each spatially periodic magnetic field includes at least two wavelengths.

4. A method of analyzing a test material comprising:

providing a first meandering primary winding for imposing a first spatially periodic magnetic field in the test material, the magnetic field being periodic in a first direction;

providing a second meandering primary winding for imposing a second spatially periodic magnetic field in the test material, the second spatially periodic magnetic field being of the same periodicity as the first spatially periodic magnetic field, being periodic in the first direction and being offset from the first spatially periodic magnetic field by a fraction of a wavelength of the magnetic fields in the first direction;

scanning the first and second meandering primary windings across the test material in a direction transverse to the first direction; and

analyzing a response of the magnetic field to the test material as the first and second meandering primary windings are scanned across the test material.

5. A method as claimed in claim 4 wherein the fraction of a wavelength is one quarter wavelength.

6. A method as claimed in claim 4 wherein each spatially periodic magnetic field includes at least two wavelengths.